cards. Three different cards can be laid out to form a three-digit number; each card is used at most once per number, although several cards may show the same digit.
The number cannot start with zero. How many **distinct even** three-digit numbers can you lay out?cards=[2, 5, 8] → 4
An even card must go last: 258, 528, 582 and 852, four numbers.
cards=[0, 4, 4] → 2
Zero cannot lead, so only 404 and 440 are possible.
cards=[3, 7, 9] → 0
There is no even digit, so no even number can be built.
cards=[2, 5, 8]
4
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